Wireless LAN Signal Collision Avoidance via NAV Setup
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Solution Overview
Problem
The coexistence of wireless LAN systems based on different communication protocols, such as HiSWANa/HiperLAN/2 and IEEE802.11a, leads to signal collisions due to differing communication initiation methods, making it difficult to use mixed systems effectively.
Innovation Solution
A wireless LAN system that includes no-signal section determining means and scheduling means to transmit communication disable or channel in use signals, preventing collisions by identifying and managing no-signal sections in the communication frame, ensuring that channels are reserved or indicated as in use, even when systems with fixed and wait-based communication methods coexist.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If wireless LAN systems with fixed-interval communication (HiSWANa/HiperLAN/2) and wait-based communication (IEEE802.11a) coexist in the same radio area, then system versatility and adaptability are improved, but signal collisions occur between the two systems
Solution Approach 1:
The access point transmits a reserved signal in advance during the no-signal section before IEEE802.11a stations can detect channel vacancy and initiate transmission. This preliminary action reserves the channel for the fixed-interval system, preventing collisions before they occur.
Solution Approach 2:
The reserved signal acts as an intermediary mechanism between the two different communication systems. It mediates the conflict by informing IEEE802.11a stations that the channel is occupied, allowing coexistence without direct interference between the systems.
2Productivity
If the access point transmits data continuously in fixed intervals, then communication efficiency is improved, but no-signal sections are created that can be exploited by other wireless LAN systems
Solution Approach 1:
The invention converts the harmful no-signal section into a beneficial reserved signal transmission opportunity. Instead of leaving the channel vulnerable during idle periods, the system uses these gaps to transmit reserved signals that protect against channel theft by other systems.
3Reliability
If the access point waits for channel vacancy before transmitting, then collision avoidance is improved, but communication delay increases and productivity decreases
Solution Approach 1:
The access point performs preliminary channel reservation by transmitting reserved signals during no-signal sections before actual data transmission begins. This allows the system to maintain high productivity while ensuring collision avoidance through advance channel reservation.
Data Source
AI summary
The present invention discloses a wireless LAN system and a signal collision avoidance method for the wireless LAN system, which can avoid the collision of signals between a wireless LAN system initiating communication at fixed intervals and a wireless LAN system initiating communication after waiting for the vacancy of a channel. According to the present invention, when it is recognized that there is a no signal section between a downlink phase and an uplink phase upon scheduling of a communication frame, a scheduler part 6 performs scheduling for putting a NAV setup signal, which covers the no signal section, behind the downlink phase in accordance with instructions from a NAV setup signal generating part 8, and transmits the same. It can prevent any station in an IEEE802.11a wireless LAN system from transmitting data in the no signal section, and hence avoid the collision of signals within the period of the uplink phase.